Frame member for electromagnetic interference shielded panel

ABSTRACT

An electromagnetic interference shielded panel and method of manufacture. The panel includes one or more frame members having a rib adapted to provide sacrificial material when a first skin member is welded to the frame member. The first skin member is welded to the frame members of a frame assembly prior to bonding of a core member and a second skin member to the first skin member and frame assembly.

RELATED APPLICATIONS

This application is a division of application Ser. No. 11/770,287, filedJun. 28, 2007.

BACKGROUND

The present disclosure is directed to an electromagnetic interferenceshielded panel and method of construction.

Enclosures, such as shelters or containers, often contain equipment,such as electrical equipment, that may be adversely affected byelectromagnetic waves. It is therefore desirable to construct theenclosure with panels that provide shielding against the passage ofelectromagnetic waves through the panel and into the enclosure tothereby shield the contents of the enclosure from electromagneticinterference.

SUMMARY

An electromagnetic interference shielded panel is disclosed for use inconstructing an electromagnetic interference shielded enclosure. Thepanel includes a peripheral frame assembly having one or more framemembers. Each frame member includes a first side wall extending betweena first end and a second end, and a second side wall extending between afirst end and a second end. An end wall is connected to the second endof each of the first side wall and second side wall. A base wall extendsbetween the first ends of the first side wall and the second side wall.First and second inclined walls extend respectively between the firstside wall and the end wall and the second side wall and the end wall.

The first side wall of the frame member includes a first surfaceextending from a first end to a second end, and a lip extendingoutwardly from the second end of the first surface to an outer end. Thefirst surface and the lip form a first recess. The first side wall alsoincludes a second surface extending from a first end to a second endwith the first end of the second surface located at the outer end of thelip. A rib extends outwardly from the second end of the second surface.The first side wall also includes a third surface extending between afirst end and a second end. The rib extends outwardly from the first endof the third surface. A second recess is formed between the secondsurface and the rib.

The panel also includes a first skin member having a peripheral edge.The edge of the first skin member is located in the second recess of thefirst side wall of the frame member and is adapted to be welded to therib and thereby to the first side wall of the frame member. The weldbetween the edge of the first skin member and the first side wall of theframe members may be substantially continuously formed. A second skinmember having a peripheral edge is coupled to the second side wall ofthe frame member and is spaced apart from the first skin member. A coremember is located between the first and second skin members.

The electromagnetic interference shielded panel is formed by providing aframe assembly including one or more frame members. The first skinmember is inserted into the second recess of the first side wall of theframe members, and the edge of the first skin member is located closelyadjacent to the ribs of the frame members. The edge of the first skinmember is then welded along the rib to the first side wall of each framemember. The core member is then placed adjacent to an interior surfaceof the first skin member. The second skin member is then placed adjacentthe core member, and the edge of the second skin member is attached tothe second side wall of the frame members.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a partial side elevational view of the electromagneticinterference shielded panel of the present disclosure.

FIG. 2 is a cross sectional view of the panel taken along line 2-2 ofFIG. 1.

FIG. 3 is a cross sectional view of a frame member.

FIG. 4 is a partial cross sectional view showing the ends of two panelsjoined to one another with the panels at a right angle.

FIG. 5 shows the ends of two panels joined to one another with thepanels in alignment with one another.

DETAILED DESCRIPTION

The electromagnetic shielded panel 20 as shown in FIGS. 1 and 2 may bejoined to a plurality of additional panels 20 by welding to form anenclosure, such as a shelter or container, having an interior chamber orspace that is shielded from external sources of electromagneticinterference (EMI). The enclosure may be formed in variousconfigurations as desired. The panel 20 as shown in FIGS. 1 and 2 isgenerally rectangular and generally planar. The panel 20 may be formedwith various height and width dimensions as desired for constructingenclosures of different desired sizes. The panel 20 may be formed invarious different configurations as desired, including, but not limitedto polygonal-shaped, curvilinear-shaped, I-shaped, T-shaped, L-shapedand other configurations.

The panel 20 includes a peripheral frame assembly 22 including one ormore frame members 24. The panel 20 as shown in FIG. 1 includes fourframe members 24 attached end to end in a generally rectangularconfiguration. The frame members 24 may be attached to one another toform a frame assembly 22 in various different configurations as desired,including, but not limited to polygonal-shaped, curvilinear-shaped,I-shaped, T-shaped, L-shaped and other configurations. Each frame member24 extends between a first end 26 and a second end 28 along a generallylinear central axis 30. As shown in FIG. 3, each frame member 24includes a first side wall 34 that extends between a first end 36 and asecond end 38, and a generally planar second side wall 40 that extendsbetween a first end 42 and a second end 44. The second side wall 40 isspaced apart from and generally parallel to the first side wall 44. Theframe member 24 also includes a generally planar base wall 46 extendingbetween a first end 48 and a second end 50. The first end 48 of the basewall 46 is attached to the first end 36 of the first side wall 34 andthe second end 50 of the base wall 46 is attached to the first end 42 ofthe second side wall 40. The base wall 46 is located generallyperpendicular to the first and second side walls 34 and 40. A generallyplanar end wall 52 extends between a first end 54 and second end 56 andis spaced apart from and generally parallel to the base wall 46. Agenerally planar first inclined wall 58 extends between a first end 60and a second end 62. The first end 60 of the first inclined wall 58 isattached to the second end 38 of the first side wall 34. The second end62 of the first inclined wall 58 is attached to the first end 54 of theend wall 52. The first inclined wall 58 is disposed at an angle ofapproximately 45° to the first side wall 34 and the end wall 52. Thesecond inclined wall 64 includes a first end 66 and a second end 68. Thefirst end 66 of the second inclined wall 64 is attached to the secondend 44 of the second side wall 40. The second end 68 of the secondinclined wall 64 is attached to the second end 56 of the end wall 52.The second inclined wall 64 is disposed at an angle of approximately 45°to the second side wall 40 and the end wall 52. The walls 34, 40, 46,52, 58 and 64 form a hollow chamber 70 within the frame member 24. Eachof the walls 34, 40, 46, 52, 58 and 64 extend from the first end 26 tothe second end 28 of the frame member 24. The first inclined wall 58 andsecond inclined wall 64 may be disposed at other angles as desired. Forexample, the walls 58 and 64 may be inclined at an angle ofapproximately 22.5° with respect to the side walls to provide achamfered effect at a corner of the enclosure, or at another angle toprovide for a more aerodynamic shape or configuration of the enclosure.Enclosures of various configurations may thereby be formed with thepanels 20.

The second side wall 40, base wall 46, end wall 52, and first and secondinclined walls 58 and 64 each include a generally planar inner surfaceand a generally planar outer surface. The first side wall 34 includes agenerally planar first surface 80 that extends between a first end 82and a second end 84. The first end 82 of the first surface 80 is locatedat the first end 36 of the first side wall 34. A generally planar lip 86extends outwardly from the second end 84 of the first surface 80,generally perpendicular to the first surface 80, to an outer end. Thefirst surface 80 and the lip 86 form a first recess 88 in the first sidewall 34.

The first side wall 34 of the frame member 24 also includes a generallyplanar second surface 92 extending between a first end 94 and a secondend 96. The first end 94 of the second surface 92 is located adjacentthe outer end of the lip 86. The second surface 92 is generally parallelto the first surface 80 and is spaced outwardly from the first surface80 with respect to the central axis 30 of the frame member 24. Anelongate generally linear sacrificial rib 98 is located at the secondend 96 of the second surface 92 and extends outwardly from the secondsurface 92. The rib 98 and the second surface 92 form a second recess100 in the first side wall 34 of the frame member 24. The rib 98provides sacrificial material for use in joining a skin member to theframe member 24. The rib 98 may be generally rectangular in crosssection, having a generally planar end surface and two generally planarside surfaces. The rib 98 may be approximately 0.05 inch high byapproximately 0.05 inch wide. The rib 98 extends from the first end 26to the second end 28 of the frame member 24.

The first side wall 34 of the frame member 24 also includes a generallyplanar third surface 104 extending between a first end 106 and a secondend 108. The third surface 104 is generally parallel to the firstsurface 80 and the second surface 92. The third surface 104 is spacedoutwardly from the second surface 92 and also forms the second recess100 with the second surface 92. The second end 108 is located at thesecond end 38 of the first side wall 34. The first surface 80, secondsurface 92 and third surface 104 are each exterior surfaces of the firstside wall 34, and each surface extends from the first end 26 to thesecond end 28 of the frame member 24.

The rib 98 is located on the first side wall 34 a distance greater thanone-half of the distance between the first end 36 and second end 38 ofthe first side wall 34, and may be located approximately three-quartersof the distance between the first end 36 and second end 38 of the firstside wall 34 from the first end 36, such that the rib 98 is located moreclosely to the second end 38 of the first side wall 34 than the firstend 36. The rib 98 may be located in an alternate position on theexterior of the frame member 24 if desired.

The walls of the frame member 24 may be integrally attached to oneanother, and the frame member 24 may be formed as an extrusion. Thewalls of the frame member 24 may be approximately 0.06 inch thick. Theframe member 24 may be formed from metal, such as aluminum, for exampleseries 6000 aluminum. The frame member 24 may be formed from anelectrically conductive material.

The panel 20 includes a generally planar first skin member 120, whichmay be located in the interior of the enclosure. The first skin member120 extends between a left end 122 and a right end 124, and between abottom end 126 and a top end 128. The first skin member 120 is generallyrectangular as shown in FIG. 1 for use with a generally rectangularframe assembly 22, such that each end includes a generally linear edge130. The first skin member 120 includes a plurality of generally linearedges 130 that form a peripheral edge. The first skin member 120includes a peripheral edge configuration, and has an overallconfiguration, that corresponds to the configuration of the frameassembly 22. The first skin member 120 includes a generally planar innersurface 132 and a generally planar outer surface 134. Each edge 130 ofthe first skin member 120 is adapted to be respectively located withinthe second recess 100 of the first side wall 34 of a frame member 24,such that the inner surface 132 of the first skin member 120 is parallelto and in engagement with the second surface 92 of the first side wall34. The edge 130 of the first skin member 120 is located closelyadjacent to, and may be in abutment with, the rib 98 such that the edge130 of the first skin member 120 may be continuously welded to the rib98 and first side wall 34 with a weld 136. The thickness of the firstskin member 120 may be approximately equal to the offset distancebetween the second surface 92 and third surface 104, such that the outersurface 134 of the first skin member 120 is generally coplanar with thethird surface 104 of the frame member 24. The frame assembly 22 extendsaround the perimeter of the first skin member 120.

The first skin member 120 may be formed from a relatively thin plate orsheet of material having a thickness of approximately 0.025 inch. Thefirst skin member 120 may be formed from metal, such as aluminum, forexample 6061-T6 aluminum. The first skin member 120 may be formed froman electrically conductive material.

The panel 20 also includes a second skin member 140. The second skinmember 140 is generally planar and extends between a left end 142 and aright end 144, and between a bottom end and a top end. The second skinmember 140 is generally rectangular as shown in FIG. 1 for use with agenerally rectangular frame assembly 22, such that each end includes agenerally linear edge 146. The second skin member 140 includes aplurality of generally linear edges 146 that form a peripheral edge. Thesecond skin member 140 includes a peripheral edge configuration, and hasan overall configuration, that corresponds to the configuration of theframe assembly 22. The second skin member 140 also includes a generallyplanar inner surface 148 and a generally planar outer surface 150. Thesecond skin member 140 may be formed from a relatively thin sheet orplate of material having a thickness of approximately 0.025 inch and,may be formed from a metal such as aluminum, for example 6061-T6aluminum. The second skin member 140 may be electrically conductive. Thesecond skin member 140 is spaced apart from and is generally parallel tothe first skin member 120. Each end of the second skin member 140 isadapted to overlap with the second side wall 40 of a frame member 24 forattachment to the second side wall 40 by adhesive bonding. A chamber 152is formed within the frame assembly 22 and between the first and secondskin members 120 and 140.

A core member 160 having a generally planar first surface 162 and agenerally parallel and generally planar second surface 164 is locatedwithin the chamber 152. The core member 160 extends between the firstskin member 120 and second skin member 140 and between the frame members24 of the frame assembly 22, substantially filling the chamber 152. Thecore member 160 may be adhesively bonded to the inner surface 132 of thefirst skin member 120 and to the inner surface 148 of the second skinmember 140. The core member 160 may be formed from honeycomb core Nomexmaterial.

The panel 20 may, if desired, include a first barrier member 166 locatedin the first recess 88 of the first side wall 34 of each frame member24. The first barrier member 166 extends from the base wall 46 to thelip 86 adjacent to the first surface 80, and between the first surface80 and the inner surface 132 of the first skin member 120. The barriermember 166 comprises a generally elongate rectangular strip that extendsgenerally from the first end 26 to the second end 28 of each framemember 24. The panel 20 may also, if desired, include a second barriermember 168 located between the second side wall 40 of each frame member24 and the ends of the second skin member 140. Each second barriermember 168 extends from the base wall 46 to a location adjacent the edge146 of the second skin member 140, and along the length of the framemember 24 and edge 146 of the second skin member 140.

The first barrier member 166 may be attached by adhesive bonding to thefirst surface 80 of the first side wall 34 of the frame member 24 and tothe inner surface 132 of the first skin member 120. The second barriermember 168 may be adhesively bonded to the second side wall 40 of theframe member 24 and to the interior surface 148 of the second skinmember 140, such that the second skin member 140 is attached to thesecond side wall 40 through the second barrier member 168.Alternatively, if the panel 20 does not include a second barrier member168, the inner surface 148 of the second skin member 140 may be attachedby adhesive bonding directly to the second side wall 40 of the framemember 24. The first and second barrier members 166 and 168 comprisethermal barriers. The first and second barrier members 166 and 168 maybe formed from a fiberglass epoxy laminate, such as G10/FR4, and may bea plastic sheet, laminated thermosetting, glass fiberbase, epoxy-resin,per MIL-I-24768/27. The first and second barrier members 166 and 168 areprovided to improve the insulation characteristics of the panel 20, andmay be eliminated from the panel 20 if desired.

The panel 20 is formed by attaching a plurality of frame members 24 toone another in an end-to-end relationship, such as by welding, to formthe frame assembly 22. The frame assembly 22 may be formed with fourframe members, namely, a bottom frame member, a top frame member, andtwo side frame members as shown in FIG. 1. The frame assembly 22 mayalternatively be formed with fewer or additional frame members 24 invarious configurations as desired. The first skin member 120 is thenplaced adjacent the frame members 24 of the frame assembly 22, such thateach edge 130 of the skin member 120 is inserted into a respectivesecond recess 100 of the first side wall 34 of a frame member 24 andadjacent to the second surface 92 of the first side wall 34. Each edge130 of the first skin member 120 is located adjacent to, and may abut,the rib 98 of the first side wall 34 of a respective frame member 24.Each edge 130 of the first skin member 120 is then welded, such as byarc welding, to the rib 98 and first side wall 34 of each frame member24 along the length of the rib 98 and the edge 130 of the first skinmember 120 with a substantially continuous weld 136. The rib 98 providessacrificial material along the frame member 24 that provides meltcharacteristics similar to the thin first skin member material when thefirst skin member 120 is welded to the frame member 24 with weldingmethods that require an arc and that produce heat. The first skin member120 is thereby integrally attached around its entire perimeter to theframe members 24 of the frame assembly 22 such that a continuouselectromagnetic interference seal is formed between the first skinmember 120 and the frame members 24 of the frame assembly 22. If desiredan opening may be provided through the panel 20, extending through theskin members 120 and 140 and the core member 160, to provide access tothe interior of an enclosure formed with the panel 20. The opening maybe selectively sealed by a door formed with an EMI panel.

If the panel 20 is to include a first barrier member 166, a firstbarrier member 166 is then inserted in the first recess 88 of the firstside wall 34 of each frame member 24 and is attached to the firstsurface 80 and first skin member 120 by adhesive bonding. The coremember 160 is then placed within the frame assembly 22 between the framemembers 24 and the first surface 162 of the core member 160 is attachedby adhesive bonding to the inner surface 132 of the first skin member120 and to the base walls 46 of the frame members 24. If desired, thesecond barrier members 168 may then be adhesively attached to the secondside wall 40 of each frame member 24. The second skin member 140 maythen be attached by adhesive bonding along each end of the second skinmember 140 to a respective second barrier member 168 and thereby to thesecond surface 164 of the core member 160. If the panel 20 does notinclude a second barrier member 168, the edges of the second skin member140 may be attached by adhesive bonding directly to the second side wall40 of each frame member 24.

Prior methods of constructing an EMI panel involved welding of the skinmembers to the frame member after the skin members were adhesivelybonded to the core member. The heat generated during the welding processcaused damage to the bonding. Skip welding was previously used to jointhe skin member to the frame member and cooling time would have to beprovided to minimize the amount of heat generated in order to avoiddamaging the bonding, substantially slowing the production process.

The present method of manufacture forms an EMI seal between the firstskin member 120 and the frame members 24 of the frame assembly 22 with asubstantially continuous weld prior to assembly and bonding of the coremember 116 and second skin member 140 to the first skin member 120 andframe assembly 22. This process provides a robust and continuous EMIseal around the perimeter of the panel 20 between the first skin member120 and the frame assembly 22. This process also provides a durable,highly conductive metal-to-metal joint to maximize EMI shieldingcapability. No secondary sealing processes are required. The use of thesacrificial rib 98 in the welding process avoids distorting the firstskin member 120 during welding thereby eliminating any defects thatcould be detrimental to the bonding process. The rib 98 allows heat uprates during welding to be closer for the skin member 120 and the framemember 24 than would otherwise occur without the rib 98. The rib 98 mayvary in shape and size to facilitate welding, depending on variablessuch as the thickness of the skin member and material properties. Steelbars may be used on the skin members for clamping and as a heat sinkduring welding. Because the bonding of the core member 160 and secondskin member 140 is performed after the welding process, the bondingcannot be damaged by the heat of welding. The panels 20 may be easilyvisually inspected to verify the integrity of the weld and EMI seal, andany EMI leaks in the panel can be easily repaired with basic weldingtechniques, prior to bonding of the core member 160 and second skinmember 140 to the first skin member 120 and frame assembly 22.

As shown in FIG. 4, two panels 20 can be attached to one another at aright angle relative to one another. In order to form a corner joint asshown in FIG. 4, two panels are placed at right angles with respect toone another with the first inclined wall 58 of a frame member 24 of afirst panel 20 in abutting engagement with the first inclined wall 58 ofthe frame member 24 of a second panel 20. The end wall 52 of the firstpanel 20 is attached to the end wall 52 of the second panel 20 by a weld172 that extends substantially continuously along the length of theframe members 24. If desired the third surfaces 104 of the first andsecond panels 20 may be welded to one another to provide additionalstrength and rigidity.

As shown in FIG. 5, two panels 20 may be attached end-to-end ingenerally co-planar alignment with one another. The end wall 52 of theframe member 24 of a first panel 20 is abutted against the end wall 52of the frame member 24 of a second panel 20. The inclined side walls ofthe respective frame members 24 may be attached to one another by a weld176 on one or both sides of the end walls 52.

Various features of the invention have been particularly shown anddescribed in connection with the illustrated embodiment of theinvention, however, it must be understood that these particulararrangements merely illustrate, and that the invention is to be givenits fullest interpretation within the terms of the appended claims.

1. A frame member for use with a skin member in forming anelectromagnetic interference shielded panel, said frame membercomprising: a base wall extending between a first end and a second end;a first side wall extending between a first end and a second end, saidfirst end of said first side wall attached to said first end of saidbase wall, said first side wall including a first surface extending froma first end to a second end, a lip extending outwardly from said secondend of said first surface to an outer end, said first surface and saidlip forming a first recess, a second surface extending from a first endto a second end, said first end of said second surface located adjacentsaid outer end of said first lip, and a third surface extending betweena first end and a second end, said second end of said third surfacebeing located adjacent said second end of said second surface, saidthird surface being located outwardly from said second surface such thata second recess is formed by said second and third surfaces, and anelongated rib extending outwardly from said second surface of said firstside wall; a second side wall extending between a first end and a secondend, said first end of said second side wall attached to said second endof said base wall, said second side wall being spaced apart from andgenerally parallel to said first side wall; whereby said rib providessacrificial material for welding the skin member to said first side wallof said frame member.
 2. The frame member of claim 1 wherein said rib islocated adjacent said first end of said third surface and extendsoutwardly from said third surface.
 3. The frame member of claim 1including an end wall extending between a first end and a second end, afirst inclined wall extending between said second end of said first sidewall and said first end of said end wall and a second inclined wallextending between said second end of said second side wall and saidsecond end of said end wall.
 4. The frame member of claim 1 wherein saidrib is located more closely to said second end of said first side wallthan to said first end of said first side wall.
 5. The frame member ofclaim 1 wherein said rib extends outwardly from said second surface ofsaid first side wall approximately 0.05 inch.
 6. The frame member ofclaim 5 wherein said rib has a width of approximately 0.05 inch.
 7. Theframe member of claim 1 wherein said rib extends from a first end ofsaid frame member to a second end of said frame member.
 8. The framemember of claim 1 wherein said first recess of said first side wall isadapted to receive a barrier member.
 9. The frame member of claim 1wherein said second recess of said first side wall is adapted to receivethe skin member.
 10. The frame member of claim 1 wherein said ribextends outwardly from said third surface of said first side wall.
 11. Aframe member for use with a skin member in forming an electromagneticinterference shielded panel, said frame member comprising: a base wallextending between a first end and a second end; a first side wallextending between a first end and a second end, said first end of saidfirst side wall attached to said first end of said base wall, said firstside wall including a first surface extending from a first end to asecond end, a second surface extending from a first end to a second end,said second surface being located outwardly from said first surface, anelongate rib extending outwardly from said first end of said secondsurface, and a first recess formed by said rib and said first surface; asecond side wall extending between a first end and a second end, saidfirst end of said second side wall attached to said second end of saidbase wall, said second side wall being spaced apart from a generallyparallel to said first side wall; whereby said rib provides asacrificial material for welding the skin member to said first side wallof said frame member.
 12. The frame member of claim 11 including a thirdsurface extending from a first end to a second end, a lip extendingoutwardly from said second end of said third surface, said third surfaceand said lip forming a second recess.
 13. The frame member of claim 12wherein said second end of said third surface is located adjacent saidfirst end of said second surface.
 14. The frame member of claim 12wherein said first recess is adapted to receive the skin member and saidsecond recess is adapted to receive a barrier member.
 15. The framemember of claim 11 wherein said first recess is adapted to receive theskin member.
 16. The frame member of claim 11 wherein said rib extendsoutwardly from said first surface.